Window film and vehicle using the same

ABSTRACT

A window film includes a polymer film, at least one carbon nanotube film, and a protective layer. The at least one carbon nanotube film is embedded in the polymer film. The protective layer is located on a surface of the polymer film. The at least one carbon nanotube film is located between the protective layer and the polymer film.

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application No. 200910265339.3, filed on Dec. 29, 2009, inthe China Intellectual Property Office, incorporated herein byreference.

BACKGROUND

1. Technical Field

The present disclosure relates to window films and vehicles using thesame, particularly, to a window film based on carbon nanotubes and avehicle using the same.

2. Description of Related Art

There are many types of window films available in the market for a widevariety of uses including solar heat reduction, UV protection, privacy,safety and security, decorative applications, and heat retention. Windowfilms are normally applied to the windows of buildings or vehicles toreduce the amount of infrared, visible light, and ultraviolet (UV)radiation entering windows. Window films used on vehicles also preventwindows of the vehicles from shattering, these films are intended tomaintain the integrity of glass when subject to heavy impact.

For security and reducing UV radiation, the window film includes aheavy-gauge plastic sheet and a low-emission coating layer. A lowemission coating layer is formed on the surface of the heavy-gaugeplastic sheet using a very complicated method. However, the strength ofthe heavy-gauge plastic sheet is insufficient to prevent fragmentationand the production of hazardous glass shards from concussion forces.

What is needed, therefore, is to provide a window film that providesgood protection for windows of vehicles, and a vehicle using the same.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic view of an embodiment of a window film.

FIG. 2 is a cross-sectional view taken along a line II-II of the windowfilm shown in FIG. 1.

FIG. 3 is a Scanning Electron Microscope (SEM) image of a carbonnanotube film used in a window film of one embodiment.

FIG. 4 is a schematic view of a carbon nanotube segment in the carbonnanotube film of FIG. 3.

FIG. 5 is an SEM image of at least two stacked carbon nanotube filmsused in a window film of one embodiment.

FIG. 6 is a schematic view of another embodiment of a window film.

FIG. 7 is a schematic view of one embodiment of a window film includinga composite carbon nanotube film.

FIG. 8 shows a relation between the light transmittance of the compositecarbon nanotube film and the wavelength of light.

FIG. 9 is a schematic view of one embodiment of a vehicle with a windowfilm of one embodiment.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1 and FIG. 2, one embodiment of a window film 10includes a polymer film 18, a protective layer 15, and at least onecarbon nanotube film 16 embedded in the polymer film 18 and locatedbetween the protective layer 15 and the polymer film 18. The protectivelayer 15 is disposed on a top surface of the polymer film 18 and coversthe at least one carbon nanotube film 16.

The polymer film 18 can have a curved structure or a planar structureand functions as a support with suitable transparency. The polymer film18 can be made of a flexible polymer material, such as polycarbonate(PC), polymethyl methacrylate acrylic (PMMA), polyethylene terephthalate(PET), polyether polysulfones (PES), polyvinyl polychloride (PVC),benzocyclobutenes (BCB), polyesters, or acrylic resins. The shape andsize of the polymer film 18 is not limited, and can be determinedaccording to need. For example, the polymer film 18 may be square, roundor triangular. In one embodiment, the polymer film 18 is a square sheetwith a thickness about 0.5 millimeters, which is made of PET.

Referring to FIG. 3, the carbon nanotube film 16 can be a free-standingstructure, meaning that the carbon nanotube film 16 can be supported byitself without a substrate for support. For example, if a point of thecarbon nanotube film 16 is held, the entire carbon nanotube film 16 canbe supported from that point without damage. Examples of the carbonnanotube film 16 are taught by U.S. Pat. No. 7,045,108 to Jiang et al.The carbon nanotube film 16 includes a number of successive carbonnanotubes joined end to end by Van der Waals attractive forcetherebetween, and substantially oriented along a same direction. Thecarbon nanotube film 16 can be a substantially pure structure consistingof the carbon nanotubes with few impurities and transparent. The carbonnanotube film 16 can be fixed on the polymer film 18 firmly because thecarbon nanotubes of the carbon nanotube film 16 combined end to end byVan der Waals attractive force, have good adhesion. The thickness of thecarbon nanotube film 16 can be in a range from about 0.5 nanometers toabout 100 micrometers.

Referring to FIG. 3 and FIG. 4, the carbon nanotube film 16 includes aplurality of successively oriented carbon nanotube segments 143 joinedend-to-end by Van der Waals attractive force therebetween. Each carbonnanotube segment 123 includes a plurality of carbon nanotubes 14522substantially parallel to each other, and combined by Van der Waalsattractive force therebetween. The carbon nanotubes in the carbonnanotube film 16 can be single-walled, double-walled, and/ormulti-walled carbon nanotubes.

Additionally, the carbon nanotube film 16 includes a number ofinterspaces between the carbon nanotubes of the carbon nanotube film 16that have good light transmittance. The light transmittance of thecarbon nanotube film 16 can be in a range from about 60% to about 95%.The polymer film 18 fills the interspaces of the carbon nanotube film16, which makes the carbon nanotube film 16 and the polymer film 18 forma whole structure, meaning that the carbon nanotubes of the carbonnanotube film 16 are connected to each other and form a free-standingstructure. The window film 10 has good strength because the carbonnanotubes of the carbon nanotube film 16 have strong materialproperties. The carbon nanotubes of the carbon nanotube film 16 alsohave a good UV light absorption, therefore the window film 10 will alsohave good UV light absorption. The window film 16 can protect thepassenger in the vehicle from the harmful UV light.

The strength of the window film 10 increases with an increasing numberof layers of carbon nanotube films 16. Additionally, if the carbonnanotubes in the carbon nanotube films 16 are aligned along onepreferred orientation, an angle can exist between the orientations ofthe carbon nanotubes in adjacent carbon nanotube films 16. Adjacentcarbon nanotube films 16 can be combined by the Van der Waals attractiveforce therebetween. An angle between the aligned directions of thecarbon nanotubes in two adjacent carbon nanotube films 16 can range fromabout 0 degrees to about 90 degrees.

A method for combining the at least one carbon nanotube film 16 with thepolymer film 18 includes:

(a) providing a layer of the polymer film 18;

(b) providing at least one carbon nanotube film 16;

(c) disposing the at least one carbon nanotube film 16 on a surface ofthe layer of the polymer film 18 to form a preform; and

(d) hot pressing the preform to combine the at least one carbon nanotubefilm 16 with the layer of the polymer film 18.

Referring to FIG. 5, one embodiment of a window film 10 includes 4layers of carbon nanotube films 16 stacked one on top of another, withan angle between the aligned directions of the carbon nanotubes in twoadjacent carbon nanotube films 16 being about 90 degrees. There are anumber of micropores between the carbon nanotubes of the crossed carbonnanotube films 16. The polymer material of the polymer film 18 can fillin the micropores to ensure the carbon nanotube films 16 is combinedtightly with the polymer film 18.

Referring to FIG. 2, the protective layer 15 covers and protects the atleast one carbon nanotube film 16. The protective layer 15 is made of atransparent polymer, such as polycarbonate (PC), polymethyl methacrylateacrylic (PMMA), polyethylene terephthalate (PET), polyether polysulfones(PES), polyvinyl polychloride (PVC), benzocyclobutenes (BCB),polyesters, acrylic resins, or epoxy resin. The thickness of theprotective layer 15 is not limited, and can be selected according to theapplication. In one embodiment, the protective layer 15 is made of epoxyresin, with a thickness about 200 micrometers.

Referring to FIG. 6, one embodiment of a window film 20 includes apolymer film 18, a plurality of carbon nanotube films 16, and aprotective layer 15. The carbon nanotube films 16 are spaced from eachother and are disposed in the polymer film 18. The protective layer 15is disposed on a surface of the polymer film 18. The carbon nanotubefilms 16 are located between the protective layer 15 and the polymerfilm 18.

In the polymer film 18, the carbon nanotube films 16 are spaced fromeach other and alternatively positioned in the polymer film 18 betweenupper and lower layer portions of the polymer film 18, with the carbonnanotubes uniformly disposed in the polymer film 18. A number ofinterspaces defined between the carbon nanotubes, are filled in by thematerial of the polymer film 18 fills. That is, the carbon nanotubefilms 16 are soaked with and combined with the polymer film 18. Thecarbon nanotube films 16 are spaced from each other in the polymer film18 so that the strength of the window film 20 is improved.

Referring to FIG. 7, another embodiment of a window film 30 includes apolymer film 18, a composite carbon nanotube film 36, and a protectivelayer 15. The composite carbon nanotube film 36 is made of at least onecarbon nanotube film 16 and a metal layer 17. The metal layer 17 iscoated on outer surface of the carbon nanotubes of the at least onecarbon nanotube film 16. The metal layer 17 can be formed on the outersurface of the carbon nanotubes of the at least one carbon nanotube film16 by a physical vapor deposition (PVD) method such as vacuumevaporation or sputtering. The material of the metal layer 17 can begold (Au), silver (Ag), copper (Cu), nickel (Ni), palladium (Pd), ortitanium (Ti). In one embodiment, the material of the metal layer 17 isAu, with a thickness of about 10 nanometers.

Referring to FIG. 8, the composite carbon nanotube film 36 of the windowfilm 30 has low light transmittance of infrared light at a wavelengthless than 400 nanometers. The composite carbon nanotube film 36 has goodlight transmittance in the visible region at a wavelength ranging fromabout 400 nanometers to about 800 nanometers. The composite carbonnanotube film 36 has a low transmittance in the ultraviolet region at awavelength beyond about 800 nanometers. Therefore, the carbon nanotubefilm 36 has a good absorption of ultraviolet light and a good reflectionof infrared light. The window film 30 can reflect the infrared light toprevent the infrared light from entering through the windows.

Referring to FIG. 9, one embodiment of a vehicle 100 with a window film10 is provided. The window film 10 is attached on the outside surface ofthe front window of the vehicle 100. A surface of the window film 10locating the carbon nanotube film 16 faces the outside of the vehicle100. The window film 10 can also be used on the rear or the side windowsof the vehicle 100.

The application of the window films 10, 20, and 30 are not limited inthe field of vehicles; it is can also to be used in the field ofbuilding windows.

It is to be understood that the above-described embodiments are intendedto illustrate rather than limit the present disclosure. Any elementsdescribed in accordance with any embodiments is understood that they canbe used in addition or substituted in other embodiments. Embodiments canalso be used together. Variations may be made to the embodiments withoutdeparting from the spirit of the present disclosure. The above-describedembodiments illustrate the scope, but do not restrict the scope of thepresent disclosure.

1. A window film, comprising: a polymer film; at least one carbonnanotube film embedded in the polymer film, the at least one carbonnanotube film having a plurality of carbon nanotubes substantiallyaligned along a same direction; and a protective layer located on asurface of the polymer film, the at least one carbon nanotube filmlocated between the protective layer and the polymer film.
 2. The windowfilm of claim 1, wherein the at least one carbon nanotube film is afree-standing structure, and combined with the polymer film to form awhole structure.
 3. The window film of claim 1, wherein the at least onecarbon nanotube film comprises a plurality of successively orientedcarbon nanotube segments joined end-to-end by Van der Waals attractiveforce therebetween.
 4. The window film of claim 3, wherein the carbonnanotube segment comprises a plurality of carbon nanotubes substantiallyparallel to each other, and combined by Van der Waals attractive forcetherebetween.
 5. The window film of claim 1, wherein the at least onecarbon nanotube film comprises a plurality of interspaces between thecarbon nanotubes of the at least one carbon nanotube film.
 6. The windowfilm of claim 5, wherein the polymer film fills in the plurality ofinterspaces of the at least one carbon nanotube film.
 7. The window filmof claim 1, wherein each of the at least one carbon nanotube film istransparent, and has a light transmittance in a range from about 60% toabout 95%.
 8. The window film of claim 1, wherein the at least onecarbon nanotube film comprises a plurality of carbon nanotube filmspositioned in the polymer film.
 9. The window film of claim 8, whereinthe plurality of carbon nanotube films are spaced from each other. 10.The window film of claim 8, wherein the plurality of carbon nanotubefilms are stacked one on another, an angle between aligned directions ofthe carbon nanotubes in two adjacent carbon nanotube films is about 90degrees.
 11. The window film of claim 10, wherein adjacent carbonnanotube films of the plurality of carbon nanotube films are combined bythe Van der Waals attractive force therebetween.
 12. The window film ofclaim 1, wherein the polymer film is made of polycarbonate (PC),polymethyl methacrylate acrylic (PMMA), polyethylene terephthalate(PET), polyether polysulfones (PES), polyvinyl polychloride (PVC),benzocyclobutenes (BCB), polyesters, or acrylic resins.
 13. The windowfilm of claim 1, wherein the protective layer is made of polycarbonate(PC), polymethyl methacrylate acrylic (PMMA), polyethylene terephthalate(PET), polyether polysulfones (PES), polyvinyl polychloride (PVC),benzocyclobutenes (BCB), polyesters, acrylic resins, or epoxy resin. 14.A window film, comprising: a polymer film having a top surface; at leastone carbon nanotube film embedded in the polymer film, the at least onecarbon nanotube film having a plurality of carbon nanotubessubstantially aligned along a same direction; a metal layer coated on asurface of the at least one carbon nanotube film; and a protective layerlocated on the top surface of the polymer film, the at least one carbonnanotube film disposed between the protective layer and the polymerfilm.
 15. The window film of claim 14, wherein the metal layer is coatedon outer surfaces of the carbon nanotubes of the at least one carbonnanotube film.
 16. The window film of claim 15, wherein a material ofthe metal layer is gold (Au), silver (Ag), copper (Cu), nickel (Ni),palladium (Pd), or titanium (Ti).
 17. The window film of claim 14,wherein the at least one carbon nanotube film comprises a plurality ofinterspaces between the carbon nanotubes of the at least one carbonnanotube film.
 18. The window film of claim 17, wherein the polymer filmfills in the plurality of interspaces of the at least one carbonnanotube film.
 19. A vehicle, comprising: at least one window filmattached on a window of the vehicle, the at least one window filmcomprising: a polymer film; at least one carbon nanotube film embeddedin the polymer film, the at least one carbon nanotube film comprising aplurality of carbon nanotubes substantially aligned along a samedirection; and a protective layer covering at least one of surfaces ofthe polymer film and the at least one carbon nanotube film.
 20. Thevehicle of claim 19, further comprising a metal layer coated on outersurfaces of the carbon nanotubes of the at least one carbon nanotubefilm.